The present invention relates to a cylinder for a rotary press. The cylinder includes a base body and an outer body. A tempering medium can flow between the two bodies
A temperable cylinder for a rotary printing press is known from DE 197 12 446 A1. A heat exchanger consisting of several tubes is arranged inside a hollow chamber of the cylinder and in turn is surrounded by a heat-transferring stationary fluid.
EP 0 557 245 A1 discloses a temperable forme cylinder with a clamping conduit extending axially over the jacket surface. Conduits extending axially in respect to the cylinder have been cut into the cylinder in the vicinity of the periphery, through which coolant flows.
EP 0 733 478 B1 shows a friction roller embodied as a tube, wherein coolant flows through the entire hollow space between an axial conduit, through which coolant is conducted, and the tube.
A temperable double-jacket drying cylinder is known from DE-PS 929 830. Steam flows in the space between an outer jacket and an inner jacket, into which ribs have been cut in a spiral pattern.
EP 0 652 104 A1 discloses a cylinder which is provided with interior cooling to prevent the build-up of ink. For this purpose, coolant flows through an annular gap, in which spiral-shaped guide plates can also be arranged for improving the circulation.
The object of the present invention is directed to providing a cylinder of a rotary printing press.
In accordance with the present invention, this object is attained by providing the cylinder with a cylinder base body and a cylinder outer body. A tempering medium can flow between the base body and the outer body. A circumferential surface of the base body has a spiral-shaped conduit, and the outer body has an inner surface. These two surfaces define the tempering medium flow path.
The advantages which can be achieved by the present invention lie primarily in that a temperable cylinder can be produced in a cost-effective manner from simple components. Because of this, a pre-selectable temperature is achieved, which is almost evenly distributed over the entire jacket surface of the cylinder. A temperature profile which fluctuates in the circumferential direction of the cylinder or which is uneven, such as can occur, for example, in connection with individual axially extending conduits and/or with wall thicknesses which are too small in comparison with the distance of the conduits, is avoided.
In an advantageous embodiment, a chamber, through which a tempering medium is conducted, is of such dimensions in the radial direction on the inside of the cylinder jacket, that a forced flow also takes place directly on the jacket surface.
A low wall thickness of the outer body separating the jacket surface and the tempering medium is particularly advantageous in respect to the fastest possible reaction time of the tempering process, for example for inking rollers, in particular screen or anilox rollers, or for forme, transfer or satellite cylinders without a device for fastening dressings, such as bracing or clamping conduits, extending radially into the interior of the jacket surface.
In a preferred embodiment of the present invention, a wall thickness of a temperable forme or transfer cylinder having one or several clamping or bracing conduits on its shell surface is so great that the clamping conduit comes to lie entirely inside the wall.
Tempering which is even in the circumferential and in the axial directions is achieved by use of a tempering medium flowing in the axial direction through a narrow gap between the outer body and the base body of the cylinder on the entire circumference.
In a further advantageous embodiment, an even more strongly directed flow is generated by use of a groove extending spirally on the outer surface of the base body.
Cooling, by use of the above mentioned spiral conduit, is furthermore advantageous, in particular for screen or anilox rollers, wherein the outer body is supported on the strips and is therefore constructed with thin walls.